Piercing-mandrel.



No. as

RRRRRRRRRRR PIERGING MANDREL.

APPLICATION FILED '00T.2 1 1 9 0 7.

Fri-p UNITED STATES PATENT OFFICE.

ROBERT J. GARDNER, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO THE S. JARVISADAMS COMPANY, OF PITTSBURG, PENNSYLVANIA, A CORPORATION OFPENNSYLVANIA.

PIERCING MANDREL.

Specification of Letters Patent.

Patented March 3, 1908.

Application filed October 21. 1907- Serial No. 398.340.

covered new and useful Improvements in' Piercin -Mandrels, of which thefollowing is a speci cation.

My invention relates to mandrels for piercin blanks in the manufactureof seamless tu es. Its object is to provide a composite piercing mandrelwhich shall have the advantages of both steel and cast-iron mandrels,and which shall be simple in construction and comparatively cheap tomanufacture.

Referring to the drawings, Figure 1 is a longitudinal section partly inelevation of the preferred construction of my invention and Fig. 2 is asection on the line 22 on Fig. 1.

On the drawings, 1 represents the cast iron body of a piercing mandrelembodying the principles of my invention. This body is cylindricalpreferably for approximately two-thirds of its length, its upper endbeing the frustum of a cone or similar figure. It has an axial bore 2with its ends flaring as shown as 3 and 4. Within this bore is the steelsupport 5, having at one end the steel piercing point 6 and at the otherend the shank 7. The point 6 forms a continuation of the tapering end ofthe body 1 and terminates in an apex 8. The external form of my piercingmandrel does not differ essentially from those known to the art but itmay have any desired shape.

The support 5 is shaped to fit the flared ends 3 and 1 of the bore 2whereby shoulders 9 and 10 are formed, the former beneath the point 6 toprevent the forward movement of the body 1 on the support and the latterat the juncture of the shank and the support to restrain the body fromrearward movement on the shank.

The body 1 may be prevented from rotation on the support 5 in many waysbut I prefer to provide the support with a short threaded section 11.

The shank 7 is preferably tapered as shown, but it may be shapedotherwise, if desired.

I prefer to manufacture my mandrel as follows: I first form the body 5with the point 6, the shank 7, the shoulders 9 and 10 and the threads11-. I then use this as a core for casting thereon the body 1 in amanner well understood by'those conversant with the art of founding. Inthis manner, I cause the body 1 to be rigidly held on the support,because portions of the body are cast in the threads of the portion 110f the support, and I cause the shoulders 9 and 10 to be in closecontact with the body so as to form a rigid structure.

In operation the steel point will be employed for causing the initialflow of the metal along the entire axis of the blank while the cast-ironbody will be employed for the work of expanding the metal opened orpierced by the steel point.

By making the body of cast-iron instead of making the whole mandrel ofsteel, I save a large expense and at the same time I have all theadvantages of a steel mandrel by the use of the steel point. Ascast-iron produces less friction than steel in piercing, I provide amandrel having the advantages of a cast-iron mandrel.

The described mandrel is to be used on the end of the usual mandrel barwhile piercing blanks in the well-known process of manufacturingseamless tubing it may be used wherever a mandrel-head or pipe-ball isre- ALIoE E. DUFF, F. N. BARBER.-

Pa, this 17th day of

